The invention concerns a magnetic field sensor.
A magnetotransistor is, from the technological point of view, a more or less ordinary bipolar transistor so optimally designed that its electrical output characteristics, e.g. its collector current I.sub.c or its current amplification factor, are highly sensitive to the strength and orientation of a magnetic field. Known magnetotransistors have a voltage sensitivity ranging from 10 Volts/Tesla to 500 Volts/Tesla or a relative-current sensitivity ranging from 20%/Tesla to 30%/Tesla and preferably employ lateral bipolar transistors.
It is known from the reference "Investigation of the Characteristics of Silicon Lateral Magnetotransistors with Two Measuring Collectors", I. M. Mitnikova et al. Sov. Phys. Semicond. 12(1), January 1978, pp. 26-28, that among other things the magnetoconcentration has a strong influence on the sensitivity of a magnetotransistor.
It is known from the reference "Magnetic Transistors Exploit New Theory of Carrier Modulation", R. Beresford, Electronics, May 19, 1982, pp. 45-46, how a magnetic field modulates the injection of electrons into the emitter of a magnetotransistor.
Swiss Patent Application No. 3679/82, R. S. Popovic et al. describes a new concept for exploiting the magnetodiode effect.
U.S. Pat. No. 4,100,563 describes a magnetic field sensor having two collector regions and two base regions wherein the lines connecting each pair of same regions are mutually perpendicular and the magnetic field to be measured acts in a direction perpendicular to the surface of the magnetic field sensor.